Home › Immunology › Tissue Controls & More for Immunohistochemistry | CST Tech Tips

Steps

1 Understand importance of IHC controls 00:23
2 Perform positive and negative tissue controls 01:09
3 Apply isotype control as negative control 02:42
4 Test phospho-specific antibodies with phosphatase 03:16
5 Assess modification-specific antibody specificity 03:48

Immunology Cell Signaling Technology

Tissue Controls & More for Immunohistochemistry | CST Tech Tips

Protocol

Difficulty

intermediate

Steps

1

Understand importance of IHC controls

Learn why multiple control experiments are essential to demonstrate antibody specificity and sensitivity beyond initial staining observation. Single assays are insufficient; multiple experiments with different controls provide confidence in IHC results.

▶ 00:23

2

Perform positive and negative tissue controls

Compare staining in tissues known to express the target protein abundantly (positive control) versus tissues without expression (negative control) using identical protocols and reagents. If results are unexpected, troubleshoot protocol and antibody concentration before proceeding.

▶ 01:09

3

Apply isotype control as negative control

Select the same isotype as the experimental antibody and apply at identical concentration to detect non-specific signal from Fc receptor interactions or tissue stickiness. Presence of staining indicates some signal is not target-specific.

▶ 02:42

4

Test phospho-specific antibodies with phosphatase

Treat tissue samples with phosphatase enzyme to remove phosphate groups and verify phospho-specificity of the antibody. Complete abolishment of staining in treated tissues confirms the antibody requires phosphorylation.

▶ 03:16

5

Assess modification-specific antibody specificity

Design IHC control experiments using blocking peptides to test methyl, acetyl, non-phospho, and cleavage-specific antibodies. Compare staining patterns in presence of non-modified peptide versus peptide with the target modification.

▶ 03:48

🚨 Failure Case Library (16) + Submit your own case

False negative — no staining at all

Even the positive control shows no staining; expected positive regions are completely blank; the experiment failed.

💡 4 · ✓ 4

Abnormal nuclear staining (wrong subcellular localization)

Cell nuclei show strong staining when they shouldn't, or expected positive nuclei show no staining; nuclear/cytoplasmic localization is wrong.

💡 4 · ✓ 4

Complete absence of IHC signal due to reagent degradation

No staining is observed in immunohistochemistry despite proper protocol execution. Previously validated antibodies or detection kits fail to produce any signal.

💡 4 · ✓ 6

Antibody not validated for IHC application or tissue type

Complete absence of staining with antibody that works in other applications. The antibody may not recognize native protein conformation present in tissue sections.

💡 4 · ✓ 5

Isotype Control Signal Matches Test Antibody Signal

The fluorescence intensity from the isotype control is comparable to or overlaps with the test antibody signal, suggesting either no specific binding or incorrect experimental setup.

💡 5 · ✓ 5

Incorrect Positive/Negative Cell Population Ratios

The measured ratio of positive to negative cells for a given marker appears inaccurate or inconsistent. Background signals are not correctly measured, leading to improper gating and incorrect population quantification.

💡 4 · ✓ 4

Strong positive background / non-specific staining

Whole slide appears brown/diffuse stained; negative control also shows signal; impossible to distinguish true positive signal.

💡 5 · ✓ 5

Weak staining / signal too faint

Positive regions show very pale staining; barely distinguishable from negative control; signal appears dotted or discontinuous.

💡 5 · ✓ 5

Target protein absent or below detection threshold in tissue

No staining observed in experimental tissue samples. The target protein may not be expressed in the tissue type or developmental stage being examined, or present at undetectable levels.

💡 4 · ✓ 6

Incorrect Use of Isotype Controls for Gating Dim Markers

Gates set using isotype controls for dim or activation markers result in inaccurate population identification, with either false negatives (missed positive cells) or false positives.

💡 4 · ✓ 5

Inappropriate Control Type Selected for Experiment

Control used does not address the main source of background in the experiment, leading to incorrect gating and data interpretation. Results are inconsistent or unreliable despite using controls.

💡 4 · ✓ 5

Weak or absent signal from inadequate antibody concentration or incubation

No detectable staining despite proper protocol execution. Insufficient antibody-antigen binding due to suboptimal concentration or incubation conditions.

💡 4 · ✓ 5

Primary-secondary antibody incompatibility preventing detection

No signal detected despite proper primary antibody binding. Secondary antibody fails to recognize or bind to the primary antibody, breaking the detection chain.

💡 4 · ✓ 5

Non-specific Antibody Binding Creating Noise

Antibody binds non-specifically to cells of interest, resulting in noisy data and elevated background. True marker expression cannot be distinguished from non-specific binding events.

💡 4 · ✓ 5

Isotype Control Does Not Match Test Antibody Background

Isotype control fails to accurately represent the non-specific binding background of the test antibody. Background levels measured by isotype control differ significantly from actual test antibody background.

💡 4 · ✓ 5

Poor Signal-to-Noise Ratio with Dim Fluorophores on Weak Markers

Weak or low-abundance markers show poor separation from negative populations and isotype controls, especially when conjugated to dim fluorophores, making population discrimination difficult.

💡 4 · ✓ 6

💬 Comments coming soon